The correct answer is D. All the above.
Inlets are provided on the road surface at the lowest point for draining rain water. This is to prevent water from pooling on the road surface, which can cause accidents. Inlets are generally provided at an interval of 30 m to 60 m along straight roads. This is to ensure that there is always an inlet available to drain water away from the road surface. Inlets having horizontal openings, are called horizontal inlets. These inlets are designed to collect water from a large area and direct it into the drainage system.
Here are some additional details about inlets:
- Inlets are typically made of concrete or plastic.
- They have a grate or screen to prevent debris from entering the drainage system.
- Inlets are connected to a pipe that carries the water away from the road surface.
- Inlets are an important part of the drainage system and help to keep roads safe and dry.